Comparison between units

Questions, comments and suggestions about the Design Navigator R-value calculator

Comparison between units

Postby simonfeek » Mon Oct 30, 2017 3:04 pm

Hi Albrecht,

Please can you help?
Apologies if there is a thread already or this question has been previously asked. But I have been wondering about the answer to this question for awhile now

The R value the Construction R-value Calculator refers to a value of XXm2K/W and clause H1 refers to R-values XXm2 deg C/W.

How are they comparable, equated, converted?

Thanks

Simon Feek
SPF AD
simonfeek
 
Posts: 5
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Re: Comparison between units

Postby simonfeek » Mon Oct 30, 2017 3:26 pm

Hi Albrecht,

Sorry Mistake on my part .... just checked again.
Some Design Navigator R-value Calculations refer to values R XXm2 deg C/W (retaining wall, roof) and some R XXm2 K/W (walls, floor),

So some are directly comparable with H1 and some (walls and floors are XXm2 K/W) and are not, and require equating?

Thanks again

Simon Feek
SPF AD
simonfeek
 
Posts: 5
Joined: Tue Jul 28, 2009 3:11 pm

Re: Comparison between units

Postby Albrecht Stoecklein » Mon Oct 30, 2017 3:34 pm

Hi Simon,

I thought I had updated all of them. Maybe you need to clear your browser cache to see them all with consistent units.

However, it is really just a naming issue. The numbers are the same.

The “K” stands for Kelvin, the “°C” obviously for degree Celsius.

Kelvin is the technically correct unit, however, the only difference between the two is that Kelvin measures temperature in absolute terms whereas °C has its 0 value at the freezing point of water. So 0°C is the same as 274.15K. 10°C is the same as 284.15K, etc..

The R-value describes the heatloss if there is a 1°C temperature difference between the two sides of the insulation material. But a 1°C temperature difference is of course the same as a 1K temperature difference. So the two R-value units are interchangeable.

I hope that clarifies it.
Albrecht Stoecklein
 
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Re: Comparison between units

Postby simonfeek » Mon Oct 30, 2017 5:05 pm

Thanks Albrecht.

Much more concisely explained than other websites I tried to find answers from.

Regards

Simon Feek
SPF AD
simonfeek
 
Posts: 5
Joined: Tue Jul 28, 2009 3:11 pm

Re: Comparison between units

Postby Tominywa » Thu Dec 14, 2017 11:12 pm

Thank you for your advice It was very helpful to me.
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